Serger Stitch Settings for TTT Pocket Trainers?

[newdsmomma]

What serger stitch and stitch settings do folks usually use on trainers with fleece leg and waist bands?

I'm making Tinkle Time nighttime pocket trainers with fleece side panels and fleece leg and waist bands (so that's four layers of fleece in some sections) and am noticing that my stitches are much bigger than the professionally made Ladder Hill Tinkle Time trainers I bought.

I've been using a 4-thread stitch on what I think is the narrowest setting my serger can do, but it still seems almost twice as wide as the seams I see on the professionally made ones. The length seems OK, but the seams are so wide they seem kind of stiff like they might be uncomfortable for my little one. Should I be using a 3-thread stitch? I was afraid that might be a problem with so many layers of fleece, but maybe not. I'm not very experienced or knowledgeable about serger stitches, but I have a good machine (Babylock Imagine).

Advice? What stitch width and length do you folks use?